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The isothermal luminescence and thermoluminescence of squalane and its solutions has been studied following irradiation with γ-rays at 77 K. The main solute used was biphenyl which gives excimer fluorescence under these conditions as well as monomer emissions. The luminescence is ascribed to ion recombination. It is only necessary to postulate two kinds of electron trapping, in the solvent or as solute anions, but there are five recombination processes giving glow peaks. If electron-attaching solutes are absent, the dominant process is thermal release of trapped electrons at ∼100 K. In solutions of biphenyl most electrons form anions; these recombine with biphenyl cations when large molecules become mobile at the glass transition (∼180 K). Close ion pairs can also decay by electron tunnelling: this produces the isothermal luminescence at 77 K. At intermediate temperatures, there is a peak ascribed to thermally assisted tunnelling; this process becomes predominant at very high concentrations. Oxygen appears to act as a carrier of electrons between anions and cations, giving an extra peak, with a high proportion of phosphorescence, below the glass-transition. Carbon dioxide and sulphur hexaflouride also have striking effects on the glow-curves. Scavenging at 77 K can be distinguished from scavenging in the melting glass.

Photolysis of a range of benzyltrimethylammonium and 3,5-dimethoxybenzyltrimethylammonium salts in water or methanol at 253.7 nm gave typically benzyl alcohols (or benzyl methyl ethers), toluenes, bibenzyls and isomers, and di- and tri-methylammonium salts. By detailed sensitisation and quenching experiments it was established that, in the photolysis of benzyltrimethylammonium bromide in aqueous t-butyl alcohol, benzyl t-butyl ether, benzyl alcohol, and some toluene were produced by a singlet pathway and bibenzyl by a triplet pathway. A general mechanistic scheme for all the photolyses studied is thus suggested.

Photolysis of benzyltrimethylammonium bromide in aqueous t-butyl alcohol gives benzyl t-butyl ether and some toluene by a singlet pathway with more toluene and bibenzyl by a triplet pathway, in each case via a reactive intermediate geminate pair (or pairs); analogous mechanisms are suggested for photolysis of a range of benzyltrimethylammonium salts in water or methanol.

Addition of carbenes CR21(R1= COMe, CO2Me, or CO2Et) to aliphatic and cyclic sulphides to yield sulphonium ylides was highly selective, whereas the addition of nitrenes NR2(R2=p-MeC6H4SO2 or CO2Et) to give iminosulphuranes was quite unselective.

Photogenerated bisalkoxycarbonyl- and diacetyl-carbenes add exclusively equatorially to 4-t-butylthian and exhibit selectivity in competitive additions to mixtures of dimethyl and di-isopropyl sulphides. By contrast ethoxycarbonyl- and p-tolysulphonyl-nitrene give equal proportions of axial and equatorial adducts with the thian, and show no selectivity in competitive reactions with dialkyl sulphides. The results in most or all cases appear to be determined by kinetic control.